Purified hydrogen is used in the manufacture of many products including metals, edible fats and oils, and semiconductors and microelectronics. Purified hydrogen also is an important fuel source for many energy conversion devices. For example, fuel cells use purified hydrogen and an oxidant to produce an electrical potential. Various processes and devices may be used to produce the hydrogen gas that is consumed by the fuel cells. Many hydrogen-production processes, however, produce an impure hydrogen stream, which may also be referred to as a mixed gas stream that contains hydrogen gas and other gases. Prior to delivering this stream to a fuel cell or stack of fuel cells, the mixed gas stream may be purified, such as to remove undesirable impurities.